Liquid-rinsed precipitation electrode for a device for precipitating and collecting charged particles from a gas



United States Patent [56] References Cited UNITED STATES PATENTS [72] inventor Ove Magnus Strindehag Nykoping, Sweden 615,973

[21] AppLNo.

55/l54TCEX 55/154TCEX 250/7l.5 250/7l.5X

m mm m 2" "m5 luv .1 mmmm NwGw 0423 2366 9999 HHHH 0582 294 051 7996 554 33 me r e n e m o t 70 67% 99g 11 4 9 12 wwm FDA 3 n dub BIS "a FPA 11.] 253 247 [[1 Stockholm, Sweden Feb. 18, 1966 Primary Examiner-Archie R. Borchelt Swede Assistant Examiner- Morton J. Frome No. 2147/66 Attorney- Pierce, Scheffler & Parker COLLECTING CHARGED PARTICLES FROM A gfi 2 Drawin H ABSTRACT: The invention is concerned with a device for g g precipitation and collection of charged particles from a gas on [52] U.S. a recipitation electrode. The electrode consists of two lel vertical wires. Water flows along the electrode and [32] Priority [54] LlQUlD-RlNSED PRECIPITATION ELECTRODE FOR A DEVICE FOR PRECIPITATING AND 250/83, paral- 250/435, 250/715, 250/102, 55/120, 55/151 forms a Int. G01t 1/20 thin film between the wires. The water thus has the dual func- Field ofSearch............................................ 250/7l.5, tion of increasing the surface of the electrode and rinsing the 83,43.5FT, R; /l51, 102, wires.

PATENTED DEEZSIHYU 355L674 Fig.1

INVENTUR Owe Ma nus sfrl ncieha ATTORNE Y5 LIQUID-RINSED PRECIPITATION ELECTRODE FOR A DEVICE FOR PRECIPITATING AND COLLECTING CHARGED PARTICLES FROM A GAS The present invention relates to a device for precipitation and collection of charged particles from a gas.

The present. invention is especially concerned with precipitation, collection and indication of radioactive parti- :les, for example such particles which escape through leakage :aused by damage to a fuel element in a nuclear reactor.

It is previously known that charged particles can be )recipitated onto an electrode that has had an electric potenial imparted to it, and that such precipitated particles can be ransported to a measuring chamber with the aid of a liquid vhich flows over the electrode.

It is also previously known to manufacture an electrode of .his type in the form of a wire along which the liquid flows, or in the form of a porous plate through which the liquid can pass. However, these known types of electrode are accomaanied by the disadvantage that it is difficult to effect a continuous, even liquid flow, and that the liquid volume must be kept fairly large, causing a low concentration of precipitated particles in the liquid. The principle object of the present invention is to arrange a device in which the liquid flow is kept absolutely even and at a minimum.

The device according to the present invention thus comprises a chamber with a delivery inlet and an outlet for the gas which carries the charged particles, a precipitation electrode situated in the chamber, a delivery inlet for the supply of a liquid to the precipitation electrode and an outlet for the liquid containing precipitated particles flowing from the precipitation electrode, being characterized in that, the precipitation electrode is comprised of at least two, parallel, ertical or inclined wires the upper ends of which are situated idjacent to the delivery inlet for the liquid which will flow ilong the precipitation electrode in the form of a liquid film aetween the wires.

The liquid forms a well-defined film that effectively washes the wires, the liquid moving at an even speed along the wires, utilizing a minimum of liquid to transport the precipitated particles to a measuring chamber.

A preferred feature of the invention is to embody the precipitation electrode with two parallel metal wires, and when the liquid is water, the wires can preferably have a diameter of 0.2-0.5 mm. being arranged at a mutual distance of approximately 2 mm. from each other. The utilization of a plurality of parallel wires is also possible, but no advantage would be gained thereby in respect of the precipitation, but would result in an undesirable increase of liquid flow in relation to the arrangement with two wires;

The invention will now be more closely described with reference to the accompanying drawing, wherein HO. 1 as an example shows an arrangement according to the invention, l-lGv 2 showing in larger scale a section along the line ll-ll in FIG. 1.

The device according to the drawing comprises a vertical metal pipe 1, which is provided with an inlet 2 and an outlet 3 for a gas. At the upper end the pipe 1 is provided with an end wall 4 of electrically insulating material. Through this end wall extends a tube 5 which is provided with a liquid delivery inlet 7. Centrally through the tube 5 extends a metal rod 6, two metal wires being secured to the lower end of the rod which is at the same level as the lower end of the tube 5. The wires 8 extend parallel to each other and coaxially to the pipe I. the lower ends of the wires being secured to a short metal rod 9 which is secured to the upper end of a coilspring 10. The lower end of the coilspring 10 being secured by means of a retainer 11 to a conduit 12 which extends through an electrically insulating end wall 13 in the bottom of the pipe 1. The lower end of the conduit 12 is connected to a measuring chamber 14, to which an outlet tube 15 is also connected. One wall of the measuring chamber is devised as a window 16, a photomultiplicator 17 being connected to the aforesaid transparent wall. I

When the illustrated arrangement is to be used to sense a possible leakage of radio active isotopes from a nuclear reactor, a flow of portative gas containing the radio active isotopes, if any, is introduced through the inlet 2. The metal rod 6 and the metal pipe 1 are then connected to an electric power source so that the metal wires 8 acquire a negative potential. Water is then introduced through the delivery inlet 7 at such a speed that a water film 18, see FIG. 2, is formed between the wires 8 and continuously runs downwards. Such radio active particles which on their decay emit an electron acquire a positive charge and as a result are attracted by the negatively charged precipitation electrode. The water with the thus precipitated particles flowing downwards along the precipitation electrode and out via the conduit 12 into the measuring chamber 14. In the chamber a Cerenkov-radiation is generated dependent upon the emission of a high energy beta or gamma radiation from the radioactive particles. Thereafter the Cerenkov-radiation is registered according to a previously known method by the photomultiplicator 17.

In the illustrated case it is preferable to measure the quantity of precipitated particles by means ofa Cerenkov-meter. Alternatively the arrangement according to the invention can be combined with, for example, a scintillometer for measurement of the radioactivity in the collected liquid, or generally with every known type of measuring device suitable for the measurement of small quantities of precipitated particles in a liquid.

lclaim:

1. A device for precipitation and collection of charged particles from a gas, comprising a chamber with a delivery port and a discharge port for-the gas, a precipitation electrode situ' ated within the chamber, a delivery port for delivering a rinsing liquid to the precipitation electrode, and a discharge port for rinsing liquid containing precipitated particles flowing from the precipitation electrode, said precipitating electrode comprising at least two parallel nonhorizontally disposed wires the upper ends of whichare so situated adjacent to the liquid-delivery port that the rinsing liquid flows along the wires in the form of a film between the wires.

2. A device according to claim 1, characterized in that the precipitation electrode comprises two metal wires of diameter 0.2-0.5 mm., the wires being situated at a mutual distance of approximately 2 mm.

3. A device according to claim 2, characterized in that the precipitation electrode extends between two electrically insulating end walls in a metal pipe.

4. A device according to claim 1, for measuring radioactive isotopes, wherein the discharge port for the liquid flowing from the precipitation electrode is connected to a measuring chamber provided with a window, a photomultiplicator being connected to said window for measuring Cerenkov-radiation generated on decay of the radioactive isotopes. 

